Standard Article

G Proteins

  1. Jeroen R Mesters,
  2. Tanis Hogg,
  3. Rolf Hilgenfeld

Published Online: 19 APR 2001

DOI: 10.1038/npg.els.0000657



How to Cite

Mesters, J. R., Hogg, T. and Hilgenfeld, R. 2001. G Proteins. eLS. .

Author Information

  1. Institute of Molecular Biotechnology, Jena, Germany

Publication History

  1. Published Online: 19 APR 2001


The G proteins, or GTP-binding proteins, can be classified into three major groups: the large mammalian Gαβγ heterotrimers, the small Ras and Ras-like GTPases, and the intermediate-sized GTPases such as elongation factors Tu (EF1A) and G (EF2). All G proteins function as molecular switches controlled by a GTPase cycle, shuttling between an active GTP–Mg2+-bound form (the ‘on’ state) and an inactive GDP–Mg2+ complex (the ‘off’ state).


  • heterotrimeric GTP-binding proteins;
  • Ras-like proteins;
  • elongation factors;
  • molecular switch;
  • signal transduction